DFT-s-OFDM Polar Interpolation for Low-PAPR Wireless Transmission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Peak-to-Average Power Ratio (PAPR) in wireless communication systems, particularly in multicarrier systems like LTE and 5G, leads to inefficiencies in power amplifiers due to higher frequency bands, requiring higher power amplifier back-offs and reduced coverage.
Innovation Solution
Implementing a DFT-s-OFDM waveform with polar domain interpolation and complex domain conversion, including phase shift keying and angle value processing to reduce PAPR, and using frequency-domain spectral shaping for optimal PAPR performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional DFT-s-OFDM waveform is used in multicarrier systems, then frequency-division multiple access is enabled, but high PAPR occurs causing power amplifier inefficiency and reduced coverage
Solution Approach 1:
The patent changes the domain in which interpolation is performed from complex domain to polar domain. By representing symbols in polar coordinates (magnitude and phase) and performing interpolation on the phase angles, the method achieves lower PAPR while maintaining the DFT-s-OFDM waveform structure and frequency-division multiple access capability
Solution Approach 2:
The patent transforms the signal representation from Cartesian coordinates (real and imaginary parts) to polar coordinates (magnitude and phase angle). This dimensional transformation allows independent processing of the phase component, enabling interpolation that avoids large phase transitions and reduces peak power variations
2Speed
If higher frequency bands are used for communication, then bandwidth capacity is increased, but PAPR effects are amplified requiring higher power amplifier back-offs
Solution Approach 1:
The patent modifies the signal generation process by performing interpolation in the polar domain rather than the complex domain. This parameter change in the processing domain reduces PAPR, which is particularly beneficial for higher frequency bands where PAPR effects are more pronounced and power amplifier back-offs are more critical for maintaining coverage
3Ease of manufacture
If complex domain interpolation is used, then waveform generation is straightforward, but large angle differences between consecutive symbols cause high PAPR
Solution Approach 1:
The patent separates the complex symbol representation into magnitude and phase components, and performs interpolation specifically on the phase angles. This dimensional separation allows the interpolation process to maintain signal continuity and avoid large phase transitions between consecutive symbols, thereby reducing PAPR while keeping the waveform generation process relatively simple
Solution Approach 2:
The patent applies different processing to different components of the complex symbol: the magnitude remains unchanged while only the phase angle undergoes interpolation. This localized processing approach targets the specific cause of high PAPR (phase transitions) without unnecessarily complicating the overall waveform generation process
Data Source
AI summary
According to an example aspect of the present disclosure, there is provided a method for transmitting a Discrete Fourier Transform-spread-Orthogonal Frequency Domain Multiplexed. DFT-s-OFDM, signal, the method comprising, converting, by a wireless transmitter, complex-valued symbols to polar domain symbols, wherein the complex-valued symbols are modulated using at least phase shift keying, processing, by the wireless transmitter, angle values of the polar domain symbols to avoid angle differences larger than π rad, or lower than −π rad, between consecutive angle values, interpolating, by the wireless transmitter, at least the processed angle values by an interpolation factor N/L, wherein L is a length of Fast Fourier Transform, FFT, and Nis length of Inverse FFT, IFFT, converting, by the wireless transmitter, the interpolated angle values into complex domain symbols and generating, by the wireless transmitter, a DFT-s-OFDM waveform comprising said complex domain symbols.